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This study examined the free vibration of a three-layered annular microplate, whose core and face sheets are composed of functionally graded saturated porous (FGSP) materials and functionally graded-graphene platelet-reinforced composites (FG-GPLRC), respectively. The microplate is supported by an elastic base, with the mechanical characteristics of all layers varying along the thickness direction. Employing the extended dynamic formulation of Hamilton’s principle, the equations of motion and boundary conditions are derived from the modified version of couple stress and first-order shear deformation theories, subsequently solved using the generalized differential quadrature method as an effective numerical approach. The study examines the impact of many parameters, including pore distributions, porosity coefficient, pore compressibility, dispersion patterns of graphene platelets, elastic foundation, small-scale parameter, and microplate aspect ratio. The results of this study may be beneficial for the construction of lightweight and sophisticated buildings.

Ruppeiner scalar curvature can be considered as an empirical tool to explore the nature of interaction among the microstructures of black holes. In the extended phase space, the phase transitions and criticality are investigated for the dyonic black holes in an ensemble, where the electric potential ${\mathrm{\Phi }}_e$ is fixed. At first, we described the thermodynamic properties of dyonic black holes to investigate the $P-V$ criticality. Further, the Ruppeiner scalar curvature is calculated in an ensemble with fixed ${\mathrm{\Phi }}_e$ utilizing the fluctuation coordinates $(T,V)$. The behavior of interactions among the microstructures of the dyonic black holes in AdS is studied where the dominance of attractive or repulsive interaction is found to be dependent on the values of electric potential ${\mathrm{\Phi }}_e$.

Size-controlled nanocrystalline silicon (nc-Si) has been prepared from a-SiN_x/a-Si:H/a-SiN_x ( 'a' standing for amorphous) sandwich structures by thermal annealing. Transmission electron microscope analyses show that the mean size and the grain size distribution (GSD) of the nc-Si are controlled by the annealing conditions and the a-Si sublayer thickness. Based on our theoretical model of constrained crystallization, we interpret the phenomena of the growth halt of nc-Si and higher crystallization temperature for the thinner a-Si sublayers. The experimental results show that constrained crystallization method is promising to achieve uniform and high density nc-Si array which can be used in the future nano-devices.

In this paper, we have synthesized meso-oxides (i.e., Co₃O₄ and NiO) by using mesoporous silica as hard template. The microstructures and chemical compositions of the corresponding meso-oxides were characterized by the Transmission electron microscope-selected area electron diffusion (TEM-SAED), X-ray diffraction (XRD), scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS), respectively. And, their electromagnetic and microwave absorption properties were investigated in the frequency range of 2–18 GHz. The results indicate that meso-oxide templated from KIT-6 (i.e., meso-K–Co/Ni) exhibit a dual absorption characteristic compared with those using SBA-15 as hard template. This phenomenon suggests that meso-oxides templated from SBA-15 and KIT-6 can exhibit different microwave absorption behaviors due to their respective microstructures.

AZ61 Mg alloy contains Al and Zn, and it has a good combination of castability, strength and ductility. However, the effect of other alloying elements on AZ61 is seldom investigated. Lead is a cheap metallic material, though its vapor is hazardous, a small amount of Pb as an alloying addition will not have significant influence on the application of Mg alloys. Studies showed that the Pb addition suppresses the formation and growth of discontinuous precipitation in AZ91 alloy. In our study, a small amount of Pb element was added into the AZ61 alloy. Mechanical properties of the alloy have been improved. The microstructures were examined by the optical microscopy (OP), scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS). The elemental distribution with Pb alloying was explicitly studied. This alloy composed of $\alpha$-Mg phase and $\beta$-Mg${}_{17}$Al${}_{12}$ phase, while Pb element inclined to distribute in $\alpha$-Mg rather than in $\beta$-Mg${}_{17}$Al${}_{12}$ phase.

The Y${}_{2.94}$Dy${}_{0.06}$Al₅O${}_{12}$ (Dy:YAG) ceramic rods were sintered at different temperatures from 1000${}^{\circ }$C to 1450${}^{\circ }$C by solid-state reaction method and the Dy:YAG single crystals were grown by the optical floating zone method. The XRD found the Y₄Al₂O₉ (YAM) phase after sintering at 1000${}^{\circ }$C and disappeared after sintering at 1450${}^{\circ }$C. The YAG phase and the YAlO₃ (YAP) phase were found in the ceramic sintered at $>$1200${}^{\circ }$C. As the sintering temperature increases, the amount of the YAG phase increases, while YAP phase decreases. There is only a single YAG phase in the Dy:YAG single crystal. The SEM images showed that the grain size in the Dy:YAG ceramic increases with the sintering temperature. There are several emission bands in the photoluminescence spectrum of the Dy:YAG single crystal located at 483 nm in the blue region, 580 nm in yellow region and 670 nm in red region. Dy:YAG is a good candidate crystal for white light emission.

This work deals with the consolidation of a TiAl alloy powder by spark plasma sintering (SPS). Pre-alloyed powder with a composition of Ti–48Al–2Cr–2Nb (at.%) was consolidated in a SPS furnace at temperatures between 1200${}^{\circ }$C and 1325${}^{\circ }$C and with a pressure of 50 MPa. The microstructures obtained after SPS depend on the sintering temperature. Tensile tests at room temperature were performed. The alloy SPSed at temperatures not less than 1250${}^{\circ }$C exhibits good properties at room temperature.

Wire arc additive manufacturing (WAAM) has received much attention for manufacturing metal parts with medium and large dimensions because of its high deposition rate and low production costs. In this study, the effects of the heat input on the microstructure formation of thin-wall low-carbon steel parts built by a WAAM process were addressed. The mechanical properties of built materials were also studied. The results indicate that the heat input significantly influences on the shape of built thin walls, but has slight effects on the microstructure evolution of built materials. The WAAM thin-wall low-carbon steel presents suitable microstructures and good tensile strengths (YS: 320 – 362 MPa, UTS: 429 – 479 MPa) that are adequate with industrial applications.

The thermal stability is important for tungsten based alloys as plasma facing materials to survive against high heat flux in fusion reactors. In this work, the thermal stability of W-5%V alloy fabricated following a powder metallurgy route by spark plasma sintering technique has been studied. To investigate the impact of temperature on the mechanical properties and microstructures, the alloy was subjected to heat treatment for 2 h over the temperature range 900–1500°C in a pure argon furnace. The micro-hardness values of the heat treated alloys were highly stable as compared to pure tungsten. A slight decrease flexural strength was observed with increasing annealing temperature. The maximum change flexural strength at the highest treated temperature was noted about 14% lower. The morphology analyses of the crack surfaces by scanning electron microscopy did not identify a drastic change in tungsten grain size, after heat treatment. The results indicate that the addition of vanadium in tungsten improves the overall thermal stability of microstructures and mechanical properties.

Tungsten and vanadium (W–V) alloys (with 1, 5 and 10 wt.% V) are fabricated by hot pressing (HP) at 1800${}^{\circ }$C under 20 MPa for 2 h. The effects of V content on the microstructures and mechanical properties of W–V alloy are investigated. The results indicate that with increasing V content, (i) the formation of W–V alloying phase is enhanced and the grain size of W-matrix is significantly refined; (ii) the relative density gradually increases from 92.16% to 97.72% in the case of pure W to W-10 wt.% V; (iii) the hardness rises linearly while the bending strength decreases, which is related to the enhanced alloy phase formation.

Selective laser melting (SLM)-fabricated AlSi10Mg parts were heat-treated under vacuum to eliminate the residual stress. Microstructure evolutions and tensile properties of the SLM-fabricated parts before and after vacuum annealing treatment were studied. The results show that the crystalline structure of SLM-fabricated AlSi10Mg part was not modified after the vacuum annealing treatment. Additionally, the grain refinement had occurred after the vacuum annealing treatment. Moreover, with increasing of the vacuum annealing time, the second phase increased and transformed to spheroidization and coarsening. The SLM-produced parts after vacuum annealing at 300${}^{\circ }$C for 2 h had the maximum ultimate tensile strength (UTS), yield strength (YS) and elongation, while the elastic modulus decreased significantly. In addition, the tensile residual stress was found in the as-fabricated AlSi10Mg samples by the microindentation method.

The NiCoCrAlYTa coating was prepared on Ni-based single crystal super-alloys by low pressure plasma spraying (LPPS). The phases and microstructures for the coatings were characterized by X-ray diffraction and scanning electron microscopy, and the fracture toughness and micro-hardness for both coatings and substrate were also investigated. The relationship between coating properties and oxidation was analyzed. The result shows that elementary distribution of NiCoCrAlYTa coatings, which consists of γ-Ni, β-NiAl, γ'-Ni₃Al, and CrCoTa phases, is much homogeneous. The composition changes with depth from the surface to substrate for the coatings. The micro-hardness of coatings is 350.8 HV_0.3 and fracture toughness is 2.73 MPa m^1/2. The oxidation resistance of coatings excelled than Ni-based single crystal super-alloys.

Pb-9.3wt.%Sb alloy was directionally solidified upwards under argon atmosphere under the two conditions; with different temperature gradients, (G = 0.93–3.67 K/mm) at a constant growth rate (V = 17.50 μm/s) and with different growth rates (V = 8.30–497.00 μm/s) at a constant (G = 3.67 K/mm) in a Bridgman furnace. The dependence of characteristic microstructure parameters such as primary dendrite arm spacing (λ₁), secondary dendrite arm spacing (λ₂) and dendrite tip radius (R) on the growth rate (V) and the temperature gradient (G) were determined by using a linear regression analysis. A detailed analysis of microstructure were also made and compared with the theoretical models and similar experimental works on dendritic solidification in the literature.

In situ synthesized TiC reinforced composite coating was fabricated by laser cladding of Al-Ni-Cr-C powders on titanium alloys, which can greatly improve the surface performance of the substrate. In this study, the Al-Ni-Cr-C laser-cladded composite coatings have been researched by means of X-ray diffraction, scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). There was a metallurgical combination between the Al-Ni-Cr-C laser-cladded coating and the Ti-6Al-4V substrate, and the micro-hardness of the Al-Ni-Cr-C laser-cladded coating was in the range of ~1200–1450 HV_0.2, which was ~3–4 times higher than that of Ti-6Al-4V substrate. Furthermore, the reinforcement of theAl-Ni-Cr-C laser-cladded coating were mainly contributed to the action of the TiC, Ti₃Al, Cr₇C₃, Al₈Cr₅ phases and the solution strengthening.

This work is based on the dry sliding wear of NiCrBSi reinforced coating deposited on TA15 titanium alloy using the laser cladding technique, the parameters of which were such as to provide almost crack-free coatings with minimum dilution and very low porosity. SEM results indicated that a laser clad coating with metallurgical joint to the substrate was formed. Compared with TA15 substrate, an improvement of the micro-hardness and wear resistance was observed for this composite coating. Rare earth oxide Y₂O₃ was beneficial in producing of the amorphous phases in laser clad coating. With addition of Y₂O₃, more amorphous alloys were produced, which increased the micro-hardness and wear resistance of the coating.

We employ the method of phase-modulated KrF excimer pulsed laser interference crystallization to fabricate nanometer-sized crystalline silicon with two-dimensional patterned distribution within the ultra-thin amouphous Si:H single-layer. The local phase transition occurs in ultra-thin a-Si:H film after laser interference crystallization under proper energy density. The results of atomic force microscopy, Raman scattering spectroscopy, cross-section transmission electron microscopy and scanning electron microscopy demonstrate that Si nanocrystallites are formed within the initial a-Si:H single-layer, selectively located in the discal regions with the diameter of 250 nm and patterned with the same 2D periodicity of 2.0 μm as the phase-shifting grating. The results demonstrate that the present method can be used to fabricate patterned nc-Si films for device applications.

Naturally occurring surfaces which display interesting surface wetting properties such as superhydrophobicity, superoleophobicity and directional wettability are found in most aquatic plants. These phenomena arise from the micro/nano structures present on these surfaces complimented by their surface chemistry. The replication of such surface structures is highly pursued due to their potential in applications such as self-cleaning (Lotus effect), microfluidic devices and antifouling surfaces. Soft lithography is a technique that has been used to replicate micro/nano structures with varying degrees of success. Nevertheless, in the context of natural surfaces, the technique has been mostly limited to the replication of the lotus leaf structure. Therefore, a systematic investigation could be fruitful since it has the potential to be scaled up to replicate different surface structures as well as large-area patterning. In this study, the feasibility of soft lithography technique on natural leaf surfaces was investigated using five plant species with different surface morphologies. The negatives of these primary molds were replicated using polydimethylsiloxane (PDMS) and the final positive replica was successfully replicated from PDMS while using hydroxypropyl methylcellulose (HPMC) as an anti-stick layer. The structures were characterized based on SEM images and contact angle measurements. Additionally, the effect of HPMC was also investigated. The technique can easily be extended to broader applications in other areas that require micro/nanostructured surfaces such as anti-reflection coatings, chemical sensors and anti-microbial surfaces.

A newly developed computational fluid dynamics method for simulating chromatographic adsorption is presented. This well-validated software package takes adsorption reactions as well as internal porosity into account to explain differences caused by the design and flow regime. Focusing on the band broadening in perfectly ordered 2D chromatographic columns, it is found that the method used for forcing the fluid through the column has a significant influence. Electro-osmosis-driven (ED) flows have a slight advantage (i.e. produce less band broadening) over pressure-driven (PD) flows. This is explained by the way the flow passes through a tortuous pore structure with changing pore size. Furthermore, this behavior does not change when the shape of the pillars is changed. Only for hexagon-like shapes is there a slight gain in performance for ED flows based on a bigger recuperation mechanism typical of ED flows in undulating pore spaces. When concentrating on the effect of the pillar, a better performance is obtained for more elongated shapes compared to more compact shapes like cylinders, as they pack in a more uniform pore space. It is also observed that the uniformity of the fluid field is the most important factor when comparing different shapes or systems. Heterogeneity in the velocity field inevitably leads to an increase of the band broadening.

A novel multiscale FE scheme is proposed for simulation of crack propagation in heterogeneous media. A fine scale mesh is constructed to model the crack tip and the microstructures around the near-tip field, while a coarse scale mesh is introduced to model the far field, wherein the effect of the microstructures is averaged through the homogenization theory to yield the average macroscopic constitutive relationship. The so-called variable node elements are subsequently employed to connect the fine scale zone in a seamless way to the coarse scale zone. The moving crack tip is modeled in a straightforward manner with the conventional quarter-point singular element. Several numerical examples are presented to demonstrate the scheme as an effective tool for multiscale simulation of crack propagation in consideration of the microstructures in a heterogeneous body.

The influence of interface strengths and microstructures on the strength and damage of SiC particle reinforced aluminum Metal Matrix Composite (MMC) is investigated under uniaxial tensile, simple shear, biaxial tensile and combined tensile and shear loadings. An algorithm to generate automatically the microstructural models of MMCs with random distribution of particle shapes, dimensions, orientations and locations is proposed and implemented within Matlab. A damage model based on the stress triaxial indicator is developed to simulate the ductile failure of metal matrix, the other damage model based on the maximum principal stress criterion is developed to simulate the brittle failure of SiC particles, and 2D cohesive element is utilized to describe interface decohesion between matrix and particles. A series of numerical experiments are performed to study the macroscopic stress–strain relationships and microscale damage evolution in MMCs under different loading conditions.